Such a system may be used, for example, as part of an adaptive cruise control in a motor vehicle. Such a control can regulate a previously set driving speed and/or a previously set distance from a vehicle in front or from objects in the direction of travel without intervention by the driver. This is done with appropriate regard for the environment around the motor vehicle and optionally additional parameters such as visibility and weather conditions. Such a control is known as an adaptive cruise control system (ACC system). The ACC system must be flexible enough to react appropriately to all driving situations, especially in view of today's growing traffic density. This in turn requires an appropriate object detection sensor system to supply the measured data required for control purposes in all driving situations.
Sensors for a freeway-capable ACC system, as a rule having radar or lidar sensors, which have a range of approximately 100 to 150 m with a detection angle of approximately 10° are known per se. Furthermore, short range distance sensors for parking aid systems which are predominantly equipped with ultrasonic sensors are also known per se.
German Patent Application No. 196 22 777 describes a sensor system for automatic determination of the relative position between two objects. This sensor system has a combination of an angle-dependent sensor and an angle-independent sensor. The sensor which does not have angle resolution and is thus independent of angle is designed as a sensor that analyzes the distance from an object on the basis of a transit time measurement. Possible sensors include RADAR, LIDAR or ultrasonic sensors. The angle-dependent sensor has a geometric arrangement of optoelectronic transmitters and receivers arranged in the form of photoelectric barriers. The sensors, both of which cover a common detection zone, are arranged in close spatial proximity. To determine the relative position of an object, the distance from the object is determined by the angle-independent sensor, and the angle to the object is determined by the sensor having angle resolution. The relative position is known on the basis of the distance from and the angle to the object. As an alternative to this arrangement of optoelectronic transmitters and receivers, the use of two sensors is proposed, which jointly determine the angle to the object by the triangulation principle.
Furthermore, an object detection system is also described in German Patent Application No. 196 16 038 in which an optical transmitter for a light beam having a variable transmission angle, and an optical receiver with angle resolution are also present. The transmitted light beam is modulated in this case in such a way that the position of the object within the angular range of the transmitted light beam can also be established up to a specific distance from the phase difference of the transmitted light beam and the received light beam.
In another object detection system described in German Patent Application No. 42 42 700, the detection of objects, particularly those a relatively large distance ahead of a vehicle, from a vehicle is made possible with a microwave radar sensor. This radar sensor is also a component of the vehicle safety system described above, in which information about the distance and the relative speed of the motor vehicle with respect to the vehicles ahead within a preset angular range, which is, however, restricted, is continuously processed.